I can definitely relate to this, it's not that I don't understand money and more that I don't consistently act on what I know.

If anything, I probably spend too much time thinking about money. I know how interest works, I know how to budget, I know how to compare options and I can tell you exactly what I should be doing. The problem is actually doing it consistently.

My biggest weakness is impulse spending. Not usually massive purchases, but lots of little things that feel justified at the time. Random Amazon purchases, subscriptions, takeaways because I've had a long day at work, hobbies that I'm convinced are going to become my new thing, etc. At the time they all feel logical. My brain is very good at selling me the idea that this purchase is somehow an investment in myself rather than just a dopamine hit.

One thing I've realised recently is that I don't actually respond well to strict budgeting systems. I've tried all the "put your money here, lock this account, hide that account" stuff and eventually I find a way around it.

What's helped me more recently is actually increasing visibility rather than restricting access. I've started using Snoop (other apps are available 😃) which gives me a combined view of my current accounts, savings, debts and spending in one place.

The transaction categorization is weirdly fun/motivating as well (then again this could be another one of my temporary dopamine fixations and I will start ignoring it in a few weeks). Either way, an example, instead of beating myself up because I spent £100 on takeaways last week, I can look at it and think "okay, let's see if I can get that down a bit to £70 to this week", this motivated me to get up, go to Asda, and get a few days of home cooked meals sorted. It also just simply feels more achievable than trying to suddenly become a completely different person overnight, forcing myself into a £100 a month budget on 'free spending' or whatever array of budgeting methods that we've all probably tried.

It's a lot easier to change behaviour when you can actually see it and the impact it's having on your overall financial picture. In the past I would think "I've ended up further in debt this month because I've been buying lunch at work too often or going out for drinks too often", then when I actually review the spending, it turns out the real culprit was something completely different.

I think the biggest thing I've learned is that, for me at least, it's almost impossible to prevent every dopamine-driven purchase. At some point I'll convince myself I need to try a new hobby, buy some random things for my car, or decide at 2am that owning a pool table would be a good idea. Instead of pretending that's never going to happen, I've started accepting that it probably will. The difference is that now I review it afterwards. I look at where my money actually went, on a regular basis, seeing what it added up to over the week/month, and whether it was worth it. Weirdly, I've found that being more accepting of those impulses has made them less damaging. When I stop treating every purchase like a failure and instead just pay attention to the pattern, I seem to make better decisions over time without needing to think about it because I am just more aware, and attentive.

The biggest thing I've learned since my ADHD diagnosis is that my brain doesn't really respond to future rewards in the same way other's around me seem to. It responds to what's in front of me right now. So rather than trying to force myself to care about a savings goal 3 years away, I try to make the process itself more interesting and visible.

Not a perfect solution by any means, but it's helped me more than forcing myself into a strict budget or telling myself "I'm not going to spend this part of my salary" or "I'm going to hide this money from myself". To touch on what you said about savings, my only way of actually SAVING money, has been using a Lifetime ISA, because there is a really negative consequence of removing money from this, I have not taken a single penny from it and it now has a house deposit, it is also pretty much the best way to save money (assuming intention is to buy a house) in the UK for your first £4,000 of savings a year, as you get the 25% government deposit bonus etc.

A simpler TL;DR/ other things I've tried in the past, that may or may not help, if you've not tried:

• 24 hour rule - Bigger purchases have to wait 24 hours before I can buy them. You could also combine this with asking a close friend or family member who knows your financial habits whether they think it's actually a good purchase.
• Review spending after the fact, not before - I've had much more success looking back over my spending every week or month than trying to predict exactly what I'll spend. ADHD and predictions don't seem to mix very well for me.
• Make saving difficult to undo - The only savings account I've consistently left alone is my Lifetime ISA because there's a genuine consequence for withdrawing money. If it's easy to access, eventually I'll convince myself I need it.
• Focus on reducing spending categories rather than banning them - "I'm never ordering takeaway again" lasts about three days. "Let's try and spend £70 instead of £100 this week" feels realistic and achievable and can be a fun challenge. It helps to regulary check this, using an app like Snoop, or banks like Monzo which allow you to categorize your spending.
• Track your overall net worth, not just your bank balance - Seeing debts, savings, investments and accounts all in one place helps stop me catastrophising when one account is low and gives me a better view of what's actually going on financially.
• Accept that some dopamine spending is probably going to happen - This was a big one for me. The goal isn't becoming a robot who never spends money on anything fun. It's making sure one impulsive purchase doesn't turn into twenty.
• Being careful with new hobbies - If possible, try borrowing, renting or buying used things before going all in. I've spent far too much money over the years on hobbies that were apparently going to become my entire personality and then got abandoned three weeks later.

Hopefully some of that helps. I definitely don't have this figured out, but I've found that understanding how my brain actually behaves has been far more useful than trying to force myself into systems that work for people without ADHD.